Please go easy on a newbie!

I've searched for this with no luck. I need to draw a ball bearing outer ring, which would be like a torus with a rectangular profile, with a semicircular cutout on the inside. I tried blending an extruded shape on a circle but got told that extrusions can't be blended. I guess if I flatten the extrusion to a shape it might work, but is there an easier way please?